21015223679 has 4 divisors (see below), whose sum is σ = 21015558384. Its totient is φ = 21014888976.

The previous prime is 21015223673. The next prime is 21015223687. The reversal of 21015223679 is 97632251012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21015223679 - 2³² = 16720256383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21015223673) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41747 + ... + 209220.

It is an arithmetic number, because the mean of its divisors is an integer number (5253889596).

Almost surely, 2^21015223679 is an apocalyptic number.

21015223679 is a deficient number, since it is larger than the sum of its proper divisors (334705).

21015223679 is an equidigital number, since it uses as much as digits as its factorization.

21015223679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334704.

The product of its (nonzero) digits is 45360, while the sum is 38.

The spelling of 21015223679 in words is "twenty-one billion, fifteen million, two hundred twenty-three thousand, six hundred seventy-nine".